Surgical component, kit and method

ABSTRACT

A surgical component, a kit including the surgical component, and a surgical method. The surgical component includes a body portion. The surgical component also includes an elongate stem for inserting into an intramedullary canal of a patient. The elongate stem extends distally from the body portion. The elongate stem has a longitudinal axis; a proximal end; a distal end; and a plurality of splines located on an outer surface of the stem. The splines are circumferentially arranged around the stem. At least some of the splines are tapered such that each tapered spline is narrower at a distal part of that spline than at a part of that spline that is proximal with respect to the distal part. The surgical component further includes an elongate neck portion extending from the body portion at a non-zero angle with respect to the longitudinal axis of the stem.

BACKGROUND

The present specification relates to a surgical component and to a kitincluding a surgical component. The present specification furtherrelates to a surgical method.

A conventional Wagner-type hip stem has a 2.5° taper along its lengthand a splined cross-section. The femoral canal is prepared using areamer and then the stem impacted into position. The splines areintended to cut into the bone to provide both axial and rotationalstability.

The degree of interference is a function of the relative size andinsertion depths of the reamer and implant. This is a well proventechnology but one drawback with current designs is that the rate ofprogression with each impaction is relatively constant, making itdifficult for a surgeon to know when they have achieved the correctlevel of resistance to prevent post-operative movement. This couldtheoretically lead to “over-seating” leading to limb shortening or“under-seating” giving insufficient resistance postoperatively.

SUMMARY

Aspects of the present disclosure are set out in the accompanyingindependent and dependent claims. Combinations of features from thedependent claims may be combined with features of the independent claimsas appropriate and not merely as explicitly set out in the claims.

According to an aspect of the present disclosure, there is provided asurgical component comprising:

a body portion;

an elongate stem for inserting into an intramedullary canal of apatient, wherein the elongate stem extends distally from the bodyportion and has:

-   -   a longitudinal axis;    -   a proximal end;    -   a distal end; and    -   a plurality of splines located on an outer surface of the stem,        wherein the splines are circumferentially arranged around the        stem, and wherein at least some of the splines are tapered such        that each tapered spline is narrower at a distal part of that        spline than at a part of that spline that is proximal with        respect to the distal part; and

an elongate neck portion extending from the body portion at a non-zeroangle with respect to the longitudinal axis of the stem.

According to another aspect of the present disclosure, there is provideda surgical method comprising using a surgical component, the surgicalcomponent comprising:

a body portion;

an elongate stem for inserting into an intramedullary canal of apatient, wherein the elongate stem extends distally from the bodyportion and has:

-   -   a longitudinal axis;    -   a proximal end;    -   a distal end; and    -   a plurality of splines located on an outer surface of the stem,        wherein the splines are circumferentially arranged around the        stem, and wherein at least some of the splines are tapered such        that each tapered spline is narrower at a distal part of that        spline than at a part of that spline that is proximal with        respect to the distal part; and

an elongate neck portion extending from the body portion at a non-zeroangle with respect to the longitudinal axis of the stem

the method comprising:

inserting the elongate stem into an intramedullary canal of a patient.

The arrangement of the tapered splines can provide a varying insertionresistance as the stem is inserted into the intramedullary canal. Thiscan provide the surgeon (or impaction system, where a Surgical AutomatedSystem (such as KINCISE™) is used) with haptic feedback as the stem isinserted. The haptic feedback may, for instance, be used to guide thesurgeon or impaction system as to when the desired seating depth of thesurgical component has been reached.

The stem and/or the elongate neck portion may be integrally formed withthe body portion. Alternatively, in other embodiments, the stem and/orthe elongate neck portion may be detachable from the body portion. Thiscan allow a modular construction of the surgical component to beachieved, in which differently sized modules (e.g. a larger or smallerstem and/or elongate neck) can be selected according to the procedure tobe performed and attached to the body portion.

Each spline may have a distal end and a proximal end. At least some ofthe tapered splines may taper along their full length from the proximaland to the distal end thereof.

The splines of at least some of the tapered splines may each have adistal region and a proximal region. Those splines may be tapered intheir distal region and may have a constant width in their proximalregion. It is also envisaged that those splines may alternatively betapered in their proximal region and may have a constant width in theirdistal region. In each spline having a tapered part in a distal (orproximal) region and a part having a constant width in a proximal (ordistal) region, an interface between the distal region and the proximalregion proximal region of that spline may be located proximally withrespect to a fixation region of the stem. The non-tapering of thesplines in the proximal (or distal) regions of the splines may preventovercrowding of the splines at the proximal end of the stem. This may,for instance, allow the tapering to be more aggressive in the distal (orproximal) regions of the splines.

The surgical component may include a plurality of further splinescircumferentially arranged around the stem.

The splines may be wider than the further splines for a majority of thelength of the splines. The splines may act as primary splines, whichprovide all or the majority of the insertion resistance, while thefurther splines may act as secondary splines, which come into contactwith the side walls of the intramedullary canal as the desired seatingdepth of the surgical component is reached.

Alternatively, the splines may be narrower than the further splines fora majority of the length of the splines.

The splines and further splines may be alternately arranged around acircumference of the stem. This can provide a surgical component havinga stem which is well balanced around the circumference of the stem. Forinstance, this can prevent tilting of surgical component as the stem isinserted, the tilting being associated with varying insertion resistancearound the circumference of the stem.

At least some of the further splines may have a constant width alongtheir full length.

At least some of the further splines may be tapered such that eachtapered further spline is narrower at a distal part of that furtherspline than at a part of that further spline that is proximal withrespect to the distal part.

The further splines may be taller than the splines, measured from thelongitudinal axis.

Alternatively, further splines may be less tall than the splines,measured from the longitudinal axis.

At least some of the splines and/or further splines may have across-sectional shape in a plane perpendicular to the longitudinal axiswhich is trapezoidal, rectangular or radiused.

The elongate stem may be tapered to be wider at its proximal end than atits distal end. The tapering of the stem and the tapering of the splinesmay combine to produce the varying insertion resistance as the stem isinserted into the intramedullary canal, providing the aforementionedhaptic feedback to the surgeon (or impaction system, where a SurgicalAutomated System (such as KINCISE™) is used).

The surgical component may be a trial component, such as a trialcomponent for trialling prior to installation of a femoral implant or ahumeral implant.

The surgical component may be a broach. The broach may be used prior toinstallation of a femoral implant or a humeral implant.

The surgical component may be a femoral implant. The method may thusinclude inserting the stem into an intramedullary canal of a femur.

The surgical component may be a humerus (shoulder) implant. The methodmay thus include inserting the stem into an intramedullary canal of ahumerus.

According to a further aspect of the present disclosure, there isprovided a surgical kit including a surgical component of the kind setout above.

The method may include receiving haptic feedback while inserting thestem into the intramedullary canal. The haptic feedback may beassociated with increasing resistance to insertion provided by thetapered splines as the stem is inserted.

During insertion of the stem into the intramedullary canal, the furthersplines may come into contact with bone defining sidewalls of theintramedullary canal immediately prior to achieving a desired seatingdepth of the surgical component.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will be described hereinafter, by way ofexample only, with reference to the accompanying drawings in which likereference signs relate to like elements and in which:

FIGS. 1A, 1B and 1C each show a surgical component comprising a surgicalimplant according to an embodiment of this disclosure;

FIG. 2 shows the stem of a surgical implant according to an embodimentof this disclosure; and

FIG. 3 shows a cross section of the surgical implant of FIG. 2, througha plane perpendicular to a longitudinal axis of the stem.

DETAILED DESCRIPTION

Embodiments of this disclosure are described in the following withreference to the accompanying drawings.

FIGS. 1A, 1B and 1C each show a surgical component according to anembodiment of this disclosure. The surgical components shown in FIG.1A-1C are surgical implants 10. Each implant 10 in the embodiments shownin FIGS. 1A-1C is designed to be installed in the femur of a patientduring hip surgery. However, it is envisaged that embodiments of thisdisclosure may instead apply to a humeral implant for shoulder surgery.The configuration of the implant in such embodiments may besubstantially as described below (particularly in relation to thesplines and/or further splines), although the overall size and shape ofthe surgical implant would be configured to allow it to be installed ina humerus instead of a femur.

Similarly, it is envisaged that in some embodiments of this disclosure,the surgical component may be a broach. The broach may be sized andshaped for use in either hip or shoulder surgery.

Similarly, it is envisaged that in some embodiments of this disclosure,the surgical component may be a trial component. The trial component maybe used in a trialling procedure prior to installation of a femoral or ahumeral implant.

Each surgical implant 10 has a body portion 50, an elongate stem 2 andan elongate neck portion 40.

In the embodiments shown in FIGS. 1A-1C, the stem 2 and the elongateneck portion 40 are integrally formed with the body portion 50.Alternatively, in other embodiments, the stem 2 and/or the elongate neckportion 40 may be detachable from the body portion 50. This can allow amodular construction of the surgical component to be achieved, in whichdifferently sized modules (e.g. a larger or smaller stem 2 and/orelongate neck portion 40) can be selected according to the procedure tobe performed and attached to the body portion 50.

Note that the stems 2 in FIGS. 1A-1C are of different lengths, accordingto the requirements of the surgical procedure in which they may be used.Thus, the stem, 2 in FIG. 1B is longer than the stem 2 in FIG. 1A, andthe stem 2 in FIG. 1C is longer than the stem 2 in FIG. 1B.

To install the implant 10, the femur (or the humerus, in the case ofshoulder surgery) may first be prepared by cutting away the femoralneck, accessing the intramedullary canal and then reaming theintramedullary canal until it is appropriately shaped to receive thestem 2. The stem 2 may then be inserted into the intramedullary canal.

The stem 2 in each embodiment has a distal end 6 and a proximal end 8.The distal end 6 of the stem 2 may form a tip of the surgical implant10. The proximal end 8 of the stem 2 joins the body portion 50. As shownin FIGS. 1A-1C, the stem 2 may be tapered such that it is wider at itsproximal end 8 than at its distal end 6. The taper angle of the stem 2may, for instance, be around 2.5°.

The stem 2 has a longitudinal axis 4, along which the stem 2 extends.When the surgical implant 10 is installed, the longitudinal axis 4 maygenerally align with a longitudinal axis of the femur (or the humerus,in the case of shoulder surgery).

The elongate neck portion 40 extends from the body portion 50 along aneck axis 42 of the surgical implant 10. As may be seen in FIGS. 1A-1C,the neck axis 42 is set at a non-zero with respect to the longitudinalaxis 4 of the stem 2, to allow the elongate neck portion 40 to emulatethe neck of the femur (or the humerus, in the case of shoulder surgery)when the surgical implant 10 is installed.

The elongate neck portion 40 may have a proximal end 44 and a distalend. The distal end of the elongate neck portion 40 may join with thebody portion 50. The proximal end 44 of the elongate neck portion 40 mayinclude a connection feature or connection features for attaching afemoral head implant (or humeral head implant, in the case of shouldersurgery) to the surgical implant 10. It is also envisaged that theproximal end 44 may be integrally formed with a femoral head part.

The stem 2 has a plurality of splines 20/30. As will be described inmore detail below in relation to FIG. 2, the splines 20/30 are locatedon an outer surface of the stem 2.

FIG. 2 shows a stem 2 of a surgical implant 10 of the kind shown inFIGS. 1A-1C according to an embodiment of this disclosure.

In this embodiment, the stem 2 includes a plurality of splines 20. Thesplines 20 are circumferentially arranged around the stem 2. Each spline20 has a distal end 26 and a proximal end 28. As can be seen in FIG. 2,the splines 20 are tapered. In particular, each spline 20 is taperedsuch that it is narrower at a distal part of that spline 20 than at apart of that spline 20 that is proximal with respect to the distal part.For instance, in FIG. 2, note that the width of each spline 20 isnarrower at location 22 than at location 24.

In this embodiment, the stem 2 also includes a number of optionalfurther splines 30. The further splines 30 are also circumferentiallyarranged around the stem 2. Each further spline 30 has a distal end 36and a proximal end 38.

In general, the further splines 30 may be configured (shaped)differently to the splines 20 in terms of their length, height, width,cross sectional shape and/or tapering (or lack of tapering).

In FIG. 2, the splines 20 and the further splines 30 may be arrangedalternately around the circumference of the stem 2, although this is notessential. Each spline 20 and/or 30 may be separated from its nearestneighbour splines 20 and/or 30 by an intervening trough 12.

In this embodiment, each further spline 30 has a substantially constantwidth along its length. However, it is also envisaged that the furthersplines 30 may be tapered. Thus, each further spline 30 may be taperedsuch that it is narrower at a distal part of that further spline 30 thanat a part of that further spline 30 that is proximal with respect to thedistal part.

Accordingly, it is envisaged that any of the tapered configurationsdescribed herein in relation to the splines 20 may also be applied tothe further splines 30.

The splines 20 and/or the further splines 30 may extend substantiallylongitudinally along the stem 2. The splines 20 and/or the furthersplines 30 may extend along substantially a full length of the stem 2.As shown in FIG. 2 however, the splines 20 and/or the further splines 30may distally terminate just short of the tip formed by the distal end 6of the stem 2. The splines 20 and/or the further splines 30 mayproximally terminate at the proximal end 8 of the stem 2, but it is alsoenvisaged that the splines 20 and/or the further splines 30 mayproximally terminate at a position located distally with respect to theproximal end 8 of the stem 2. As may be seen in FIGS. 1A-1C, it isfurther envisaged that at least some of the splines 20 and/or thefurther splines 30 may extend proximally beyond the proximal end 8 ofthe stem 2, such that they proximally terminate on the body portion 50of the surgical implant 10. It is also envisaged that the furthersplines 30 may have a different length to the splines 20. For instance,the further splines 30 may proximally terminate either proximally ordistally with respect to the splines 20 and/or the further splines 30may distally terminate either proximally or distally with respect to thesplines 20.

In FIG. 2, the splines 20 taper consistently along their length.However, it is envisaged that the tapering of the splines 20 may vary oreven halt at certain points along their length.

For instance, in some embodiments, the degree of tapering along atapered part of each spline 20 may vary. In one such example, thetapering of each spline 20 may be gradual at or near the distal end 26and increase at one or more locations along that spline 20. Thisarrangement may also be reversed, such that the tapering of each spline20 may be relatively rapid at or near the distal end 26 and decrease atone or more locations along that spline 20. These changes may providechanges in the haptic feedback provided to the surgeon (or impactionsystem, where a Surgical Automated System (such as KINCISE™) is used) asthe stem 2 is inserted into the intramedullary canal (the hapticfeedback provided by the splines 20 and/or the further splines 30 withbe described in detail below).

In one or more embodiments, at least some of the splines 20 may includenon-tapered regions. For instance, in one embodiment, at least some ofthe splines 20 each have a distal region and a proximal region, andthose splines 20 may be tapered in their distal region and have aconstant width in their proximal region. Alternatively, those splines 20may be tapered in their proximal region and have a constant width intheir distal region.

Returning briefly to FIGS. 1A-1C, note that in each FIG. , a fixationregion of the stem 2 of each implant 10 is indicated by the arrowslabelled A. Also in FIGS. 1B-1C, a tapered region of the splines 20 isgenerally indicated by the arrow labelled B and a non-tapered region ofthe splines 20 is generally indicated by the arrow labelled C. Note thatin each case, the transition from the tapered region B to thenon-tapered region C is located proximally with respect to a mostproximal part of the fixation region of the stem 2 labelled A (this mayalso be the case in embodiments in which the splines 20 are tapered intheir proximal region and have a constant width in their distal region).In the embodiment of FIG. 1A, the splines taper along their completelength (hence FIG. 1A includes a region labelled B, but no regionlabelled C),

The transition from the tapered region to the region of constant widthmay provide haptic feedback to the surgeon (or impaction system, where aSurgical Automated System (such as KINCISE™) is used) as will bedescribed below. Moreover, the provision of the non-tapered regionstowards the proximal ends 28 of the splines 20 may prevent overcrowdingof the splines towards the proximal end 8 of the stem 2 (particularly inlonger stems 2 of the kind shown in FIGS. 1B and 1C) and/or may allowthe tapering in the distal regions (or proximal regions) of the splines20 to be more rapid.

In accordance with embodiments of this disclosure, the splines 20 may bewider than the further splines 30 for a majority of the length(including the complete length) of the splines 20. An example of such aconfiguration is shown in FIGS. 2 and 3. However, it is also envisagedthat this configuration may be reversed, such that the splines 20 arenarrower than the further splines 30 for a majority of the length(including the complete length) of the splines 20.

FIG. 3 shows a cross section of the stem 2 of FIG. 2, through a planeperpendicular to a longitudinal axis 4. In this embodiment, it can beseen that the further splines 30 are less tall than the splines 20,measured radially outward from the longitudinal axis 4. The differencein height between the splines 20 and the further splines 30 (labelledusing reference numeral 32 in FIG. 3) may in the region of 0.2-0.5 mm.In the present embodiment, the difference in height 32 is about 0.25 mm.

This configuration can cause the further splines 30 to come into contactwith the sidewalls of the intramedullary canal later than the splines20. This may provide the surgeon (or impaction system, where a SurgicalAutomated System (such as KINCISE™) is used) with further hapticfeedback, as will be described below. It is envisaged that thisconfiguration may be reversed, such that the further splines 30 aretaller than the splines 20, measured radially outward from thelongitudinal axis 4.

In accordance with embodiments of this disclosure, the splines 20 and/orthe further splines 30 may have a cross sectional shape (i.e. in a planeperpendicular to the longitudinal axis) which is trapezoidal,rectangular (e.g. see FIG. 3) or radiused.

In accordance with embodiments of this disclosure, the maximum widths ofthe splines 20 and/or the further splines 30 may be around 2.8 mm, ormore preferably no wider than 2mm. The taper angle of the tapered (partsof) the splines 20 and/or the further splines 30 may be around 1°.

According to embodiments of this disclosure, there may be provided asurgical kit. The surgical kit may include one or more surgical implants10 of the kind described herein. The surgical kit may also include othercomponents such as surgical implants or surgical tools.

As mentioned previously, the configurations of the splines 20 and/or thefurther splines 30 described herein may provide haptic feedback to thesurgeon (or impaction system, where a Surgical Automated System (such asKINCISE™) is used) as the stem 2 is being inserted into theintramedullary canal of a femur (or humerus, in the case of shouldersurgery).

In embodiments in which the stem 2 of the surgical implant 10 includesthe splines 20 but not the further splines 30, the tapering of thesplines 20 may provide haptic feedback to the surgeon (or impactionsystem, where a Surgical Automated System (such as KINCISE™) is used) asfollows. The surgeon may hold the surgical implant (e.g. at the bodyportion 50 and/or the elongate neck portion 40) while manually insertingthe stem 2 into the pre-prepared intramedullary canal. When a SurgicalAutomated System (such as KINCISE™) is used, the implant 10 may insteadbe attached to an impaction system for insertion of the stem 2. As thestem 2 is inserted, the splines 20 eventually come into contact with,and begin to dig into the side walls of the intramedullary canal.Friction between the splines 20 and the sidewalls gives rise to a forcewhich resists the further insertion of the stem 2. Owing to the taperingof the splines 20, this resistive force increases as the depth of thestem 2 inside the intramedullary canal increases. This increasingresistance to insertion of the stem 2 provides haptic feedback to thesurgeon (or impaction system, where a Surgical Automated System (such asKINCISE™) is used) regarding the position of the stem 2 within theintramedullary canal and can, for example, allow the surgeon (orimpaction system) to determine when a desired seating position of thesurgical implant 10 within the femur (or the humerus, in the case ofshoulder surgery) is being approached and/or has been reached.

In embodiments in which the stem 2 of the surgical implant 10 includesthe further splines 30, The haptic feedback provided to the surgeon (orimpaction system, where a Surgical Automated System (such as KINCISE™)is used) depends upon not only of the shape and configuration of thesplines 20 and of the further splines 30, but also on the differences inshape and configuration of the splines 20 and further splines 30.

Assuming that the splines 20 are taller than the further splines 30, thehaptic feedback provided by the splines 20 may be substantially asdescribed above in relation to embodiments not including the furthersplines 30, at least until the further splines 30 come into contact withthe side walls of the intramedullary canal. This is because when thefurther splines 30 are less tall than the splines 20 (e.g. as shown inFIG. 3), the further splines 30 will come into contact with the sidewalls of the intramedullary canal sometime after the splines 20 havecontacted the side walls, and because the further splines 30 do notcontribute to the resistive force against further insertion of the stem2 until they contact the sidewalls. At some point during insertion ofthe stem 2, the further splines will nevertheless come into contact withthe sidewalls. At this point there will be a step change in theresistance force opposing further insertion of the stem 2. This stepchange may provide the surgeon (or impaction system, where a SurgicalAutomated System (such as KINCISE™) is used) with further hapticfeedback regarding the position of the stem 2 within the intramedullarycanal. For instance, in accordance with embodiments of this disclosure,the difference in height between the splines 20 and the further splines30 maybe chosen such the further splines 30 contact the side walls ofthe intramedullary canal just before the desired seating position isreached. A typical difference in height of the splines 20 and furthersplines 30 would be in the region of 0.2-0.5 mm.

As mentioned previously, the further splines 30 may themselves betapered in any of the ways described herein in the context of thesplines 20. Accordingly, once the further splines 30 have contacted theside walls of the intramedullary canal, the contribution to the overallresistive force opposing further insertion of the stem 2, which isprovided by the further splines 30, may itself vary with insertiondepth, in much the same way as that described above in relation to thesplines 20.

The further splines 30 may, in some embodiments, be taller than thesplines 20. In such embodiments, the further splines 30 would contactthe side walls of the intramedullary canal before the splines 20. Inembodiments in which the further splines 30 non-tapering and the furthersplines 30 are taller than the splines 20, the further splines 30 mayprovide a relatively constant resistive force to further insertion ofthe stem 2 until the splines 20 contact the sidewalls. In suchembodiments, the step change in resistive force associated with theinitial contact of the splines 20 with the side walls may provide hapticfeedback to the surgeon (or impaction system, where a Surgical AutomatedSystem (such as KINCISE™) is used) that the correct seating position ofthe stem 2 is being approached. Similar considerations also apply wherethe further splines 30 are taller than the splines 20 and are in someway tapered, albeit that the contribution to the overall insertionresistance provided by the tapered further splines would also changewith the insertion depth of the stem 2.

In embodiments including the further splines 30, the relativecontributions to the overall resistive force opposing further insertionof the stem 2 at a given insertion depth may also be determined byselectively tailoring the differences in height, width, cross-sectionalshape and/or taper angle of the splines 20 and the further splines 30.

According to embodiments of this disclosure, there may be provided asurgical method. The method may, for instance, form part of a hip (orshoulder) replacement or revision procedure. In general, the method maycomprise the installation of a surgical component of the kind describedherein.

To use the component, the stem 2 (e.g. the stem 2 of an implant 10 ofthe kind described above) may be inserted into the intramedullary canalof the patient's femur (or humerus, in the case of shoulder surgery). Asnoted previously, insertion of the stem 2 may be preceded by preparatorystep such as removing the neck and head of the femur (or the humerus, inthe case of shoulder surgery) and reaming the intramedullary canal tosize it for receipt of the stem 2.

As the stem 2 is being inserted, the surgeon (or impaction system, wherea Surgical Automated System (such as KINCISE™) is used) may receivehaptic feedback of the kinds described above. As such, the hapticfeedback may, for instance, be associated with the increasing resistanceto insertion provided by the splines 20 (and possibly also the furthersplines 30) as the stem 2 is inserted, and/or may be associated with thefurther splines 30 coming into contact with bone defining sidewalls ofthe intramedullary canal immediately prior to achieving a desiredseating depth of the implant.

Accordingly, there has been described a surgical implant, a kitincluding the surgical implant, and a surgical method. The surgicalimplant includes a body portion. The surgical implant also includes anelongate stem for inserting into an intramedullary canal of a patient.The elongate stem extends distally from the body portion. The elongatestem has a longitudinal axis; a proximal end; a distal end; and aplurality of splines located on an outer surface of the stem. Thesplines are circumferentially arranged around the stem. At least some ofthe splines are tapered such that each tapered spline is narrower at adistal part of that spline than at a part of that spline that isproximal with respect to the distal part. The surgical implant furtherincludes an elongate neck portion extending from the body portion at anon-zero angle with respect to the longitudinal axis of the stem.

Aspects of the present disclosure are set out in the following series ofnumbered clauses.

-   1. A surgical component comprising:

a body portion;

an elongate stem for inserting into an intramedullary canal of apatient, wherein the elongate stem extends distally from the bodyportion and has:

-   -   a longitudinal axis;    -   a proximal end;    -   a distal end; and    -   a plurality of splines located on an outer surface of the stem,        wherein the splines are circumferentially arranged around the        stem, and wherein at least some of the splines are tapered such        that each tapered spline is narrower at a distal part of that        spline than at a part of that spline that is proximal with        respect to the distal part; and

an elongate neck portion extending from the body portion at a non-zeroangle with respect to the longitudinal axis of the stem.

-   2. The surgical component of clause 1, wherein each spline has a    distal end and a proximal end, and wherein at least some of the    tapered splines each taper along their full length from the proximal    and to the distal end thereof.-   3. The surgical component of clause 1 or clause 2, wherein at least    some of the tapered splines each have a distal region and a proximal    region, wherein:

those splines are tapered in their distal region and have a constantwidth in their proximal region; or

those splines are tapered in their proximal region and have a constantwidth in their distal region.

-   4. The surgical component of clause 3, wherein, in each spline    having a tapered part and a part having a constant width, an    interface between the distal region and the proximal region of that    spline is located proximally with respect to a fixation region of    the stem.-   5. The surgical component of any preceding clause, comprising a    plurality of further splines circumferentially arranged around the    stem.-   6. The surgical component of clause 5, wherein the splines are wider    than the further splines for a majority of the length of the    splines.-   7. The surgical component of clause 5, wherein the splines are    narrower than the further splines for a majority of the length of    the splines.-   8. The surgical component of any of clauses 5 to 7, wherein the    splines and further splines are alternately arranged around a    circumference of the stem.-   9. The surgical component of any of clauses 5 to 8, wherein at least    some of the further splines have a constant width along their full    length.-   10. The surgical component of any of clauses 5 to 9, wherein at    least some of the further splines are tapered such that each tapered    further spline is narrower at a distal part of that further spline    than at a part of that further spline that is proximal with respect    to the distal part.-   11. The surgical component of any of clauses 5 to 10, wherein the    further splines are taller than the splines, measured from the    longitudinal axis.-   12. The surgical component of any of clauses 5 to 10, wherein the    further splines are less tall than the splines, measured from the    longitudinal axis.-   13. The surgical component of any preceding clause, wherein at least    some of the splines and/or further splines have a cross-sectional    shape in a plane perpendicular to the longitudinal axis which is    trapezoidal, rectangular or radiused.-   14. The surgical component of any preceding clause, wherein the    elongate stem is tapered to be wider at its proximal end than at its    distal end.-   15. The surgical component of any preceding clause, wherein the    component is:

a femoral implant,

a humeral implant.

a trial component; or

a broach.

-   16. A surgical kit including a surgical component according to any    preceding clause.-   17. A surgical method comprising using a surgical component, the    surgical component comprising:

a body portion;

an elongate stem for inserting into an intramedullary canal of apatient, wherein the elongate stem extends distally from the bodyportion and has:

-   -   a longitudinal axis;    -   a proximal end;    -   a distal end; and    -   a plurality of splines located on an outer surface of the stem,        wherein the splines are circumferentially arranged around the        stem, and wherein at least some of the splines are tapered such        that each tapered spline is narrower at a distal part of that        spline than at a part of that spline that is proximal with        respect to the distal part; and

an elongate neck portion extending from the body portion at a non-zeroangle with respect to the longitudinal axis of the stem,

the method comprising:

inserting the elongate stem into an intramedullary canal of a patient.

-   18. The surgical method of clause 17, further comprising receiving    haptic feedback while inserting the stem into the intramedullary    canal, wherein the haptic feedback is associated with increasing    resistance to insertion provided by the tapered splines as the stem    is inserted.-   19. The surgical method of clause 17 or clause 18, wherein each    spline has a distal end and a proximal end, and wherein at least    some of the tapered splines each taper along their full length from    the proximal and to the distal end thereof.-   20. The surgical method of any of clause 17 to 19, wherein at least    some of the tapered splines each have a distal region and a proximal    region, wherein:

those splines are tapered in their distal region and have a constantwidth in their proximal region; or

those splines are tapered in their proximal region and have a constantwidth in their distal region.

-   21. The surgical method of clause 20, wherein in each spline having    a tapered part and a part having a constant width, an interface    between the distal region and the proximal region proximal region of    that spline is located proximally with respect to a fixation region    of the stem.-   22. The surgical method of any of clauses 17 to 21, the stem    comprising a plurality of further splines circumferentially arranged    around the stem.-   23. The surgical method of clause 22, wherein during said insertion    of the stem into the intramedullary canal, the further splines come    into contact with bone defining sidewalls of the intramedullary    canal immediately prior to achieving a desired seating depth of the    component.-   24. The surgical method of clause 22 or clause 23, wherein the    splines are wider than the further splines for a majority of the    length of the splines.-   25. The surgical method of clause 22 or clause 23, wherein the    splines are narrower than the further splines for a majority of the    length of the splines.-   26. The surgical method of any of clauses 22 to 25, wherein the    splines and further splines are alternately arranged around a    circumference of the stem.-   27. The surgical method of any of clauses 22 to 26, wherein at least    some of the further splines have a constant width along their full    length.-   28. The surgical method of any of clauses 22 to 27, wherein at least    some of the further splines are tapered such that each tapered    further spline is narrower at a distal part of that further spline    than at a part of that further spline that is proximal with respect    to the distal part.-   29. The surgical method of any of clauses 22 to 28, wherein the    further splines are taller than the splines, measured from the    longitudinal axis.-   30. The surgical method of any of clauses 22 to 28, wherein the    further splines are less tall than the splines, measured from the    longitudinal axis.-   31. The surgical method of any of clauses 17 to 30, wherein at least    some of the splines and/or further splines have a cross-sectional    shape in a plane perpendicular to the longitudinal axis which is    trapezoidal, rectangular or radiused.-   32. The surgical of any of clauses 17 to 31, wherein the elongate    stem is tapered to be wider at its proximal end than at its distal    end.-   33. The surgical method of any of clauses 17 to 32, wherein the    surgical component is a trial implant or a broach.-   34. The surgical method of any of clauses 17 to 32, wherein the    surgical component is a femoral implant, and wherein the method    comprises inserting the stem into an intramedullary canal of a    femur.-   35. The surgical method of any of clauses 17 to 32, wherein the    surgical component is a humeral implant, and wherein the method    comprises inserting the stem into an intramedullary canal of a    humerus.

Although particular embodiments of this disclosure have been described,it will be appreciated that many modifications/additions and/orsubstitutions may be made within the scope of the claims.

1. A surgical component comprising: a body portion; an elongate stem forinserting into an intramedullary canal of a patient, wherein theelongate stem extends distally from the body portion and has: alongitudinal axis; a proximal end; a distal end; and a plurality ofsplines located on an outer surface of the stem, wherein the splines arecircumferentially arranged around the stem, and wherein at least some ofthe splines are tapered such that each tapered spline is narrower at adistal part of that spline than at a part of that spline that isproximal with respect to the distal part; and an elongate neck portionextending from the body portion at a non-zero angle with respect to thelongitudinal axis of the stem.
 2. The surgical component of claim 1,wherein each spline has a distal end and a proximal end, and wherein atleast some of the tapered splines each taper along their full lengthfrom the proximal and to the distal end thereof.
 3. The surgicalcomponent of claim 1, wherein at least some of the tapered splines eachhave a distal region and a proximal region, wherein: those splines aretapered in their distal region and have a constant width in theirproximal region; or those splines are tapered in their proximal regionand have a constant width in their distal region.
 4. The surgicalcomponent of claim 3, wherein, in each spline having a tapered part anda part having a constant width, an interface between the distal regionand the proximal region of that spline is located proximally withrespect to a fixation region of the stem.
 5. The surgical component ofclaim 1, comprising a plurality of further splines circumferentiallyarranged around the stem.
 6. The surgical component of claim 5, whereinthe splines are wider than the further splines for a majority of thelength of the splines.
 7. The surgical component of claim 5, wherein thesplines are narrower than the further splines for a majority of thelength of the splines.
 8. The surgical component of claim 5, wherein thesplines and further splines are alternately arranged around acircumference of the stem.
 9. The surgical component of claim 5, whereinat least some of the further splines have a constant width along theirfull length.
 10. The surgical component of claim 5, wherein at leastsome of the further splines are tapered such that each tapered furtherspline is narrower at a distal part of that further spline than at apart of that further spline that is proximal with respect to the distalpart.
 11. The surgical component of claim 5, wherein the further splinesare taller than the splines, measured from the longitudinal axis. 12.The surgical component of claim 5, wherein the further splines are lesstall than the splines, measured from the longitudinal axis.
 13. Thesurgical component of claim 1, wherein at least some of the splinesand/or further splines have a cross-sectional shape in a planeperpendicular to the longitudinal axis which is trapezoidal, rectangularor radiused.
 14. The surgical component of claim 1, wherein the elongatestem is tapered to be wider at its proximal end than at its distal end.15. The surgical component of claim 1, wherein the component is: afemoral implant, a humeral implant. a trial component; or a broach. 16.A surgical kit including a surgical component, the surgical componentcomprising: a body portion; an elongate stem for inserting into anintramedullary canal of a patient, wherein the elongate stem extendsdistally from the body portion and has: a longitudinal axis; a proximalend; a distal end; and a plurality of splines located on an outersurface of the stem, wherein the splines are circumferentially arrangedaround the stem, and wherein at least some of the splines are taperedsuch that each tapered spline is narrower at a distal part of thatspline than at a part of that spline that is proximal with respect tothe distal part; and an elongate neck portion extending from the bodyportion at a non-zero angle with respect to the longitudinal axis of thestem.
 17. A surgical method comprising using a surgical component, thesurgical component comprising: a body portion; an elongate stem forinserting into an intramedullary canal of a patient, wherein theelongate stem extends distally from the body portion and has: alongitudinal axis; a proximal end; a distal end; and a plurality ofsplines located on an outer surface of the stem, wherein the splines arecircumferentially arranged around the stem, and wherein at least some ofthe splines are tapered such that each tapered spline is narrower at adistal part of that spline than at a part of that spline that isproximal with respect to the distal part; and an elongate neck portionextending from the body portion at a non-zero angle with respect to thelongitudinal axis of the stem, the method comprising: inserting theelongate stem into an intramedullary canal of a patient.
 18. Thesurgical method of claim 17, further comprising receiving hapticfeedback while inserting the stem into the intramedullary canal, whereinthe haptic feedback is associated with increasing resistance toinsertion provided by the tapered splines as the stem is inserted. 19.The surgical method of claim 17, wherein each spline has a distal endand a proximal end, and wherein at least some of the tapered splineseach taper along their full length from the proximal and to the distalend thereof.
 20. The surgical method of claim 17, wherein at least someof the tapered splines each have a distal region and a proximal region,wherein: those splines are tapered in their distal region and have aconstant width in their proximal region; or those splines are tapered intheir proximal region and have a constant width in their distal region.21. The surgical method of claim 20, wherein in each spline having atapered part and a part having a constant width, an interface betweenthe distal region and the proximal region proximal region of that splineis located proximally with respect to a fixation region of the stem. 22.The surgical method of claim 17, the stem comprising a plurality offurther splines circumferentially arranged around the stem.
 23. Thesurgical method of claim 22, wherein during said insertion of the steminto the intramedullary canal, the further splines come into contactwith bone defining sidewalls of the intramedullary canal immediatelyprior to achieving a desired seating depth of the component.
 24. Thesurgical method of claim 22, wherein the splines are wider than thefurther splines for a majority of the length of the splines.
 25. Thesurgical method of claim 22, wherein the splines are narrower than thefurther splines for a majority of the length of the splines.
 26. Thesurgical method of claim 22, wherein the splines and further splines arealternately arranged around a circumference of the stem.
 27. Thesurgical method of claim 22, wherein at least some of the furthersplines have a constant width along their full length.
 28. The surgicalmethod of claim 22, wherein at least some of the further splines aretapered such that each tapered further spline is narrower at a distalpart of that further spline than at a part of that further spline thatis proximal with respect to the distal part.
 29. The surgical method ofclaim 22, wherein the further splines are taller than the splines,measured from the longitudinal axis.
 30. The surgical method of claim22, wherein the further splines are less tall than the splines, measuredfrom the longitudinal axis.
 31. The surgical method of claim 17, whereinat least some of the splines and/or further splines have across-sectional shape in a plane perpendicular to the longitudinal axiswhich is trapezoidal, rectangular or radiused.
 32. The surgical of claim17, wherein the elongate stem is tapered to be wider at its proximal endthan at its distal end.
 33. The surgical method of claim 17, wherein thesurgical component is a trial implant or a broach.
 34. The surgicalmethod of claim 17, wherein the surgical component is a femoral implant,and wherein the method comprises inserting the stem into anintramedullary canal of a femur.
 35. The surgical method of claim 17,wherein the surgical component is a humeral implant, and wherein themethod comprises inserting the stem into an intramedullary canal of ahumerus.